Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Clamp
The present invention relates to a clamp for suspending a utility component
from a
structural element (such as a beam) comprising first and second jaws having
opposing
contact surfaces which are relatively substantially linearly displaceable.
A conventional beam or flange clamp for suspending a utility component from a
structural element such as a beam comprises a main body which is drilled or
tapped at
its rear portion in order to secure a drop rod outside and separate to the
clamping region
by means of rivets or bolts. The operation of this clamp is illustrated
schematically in
Figures la and 1b. A beam (or flange thereof) 7 is inserted in jaws 1 and
clamped
directly by appropriate manipulation of cup point set screw 2 and locking nut
3. A rear
portion of the main body 5 is provided with a tapped or clear hole 4 for
securing a
threaded or non-threaded drop rod respectively (not shown in Figure la).
Figure 1b
illustrates the use of the clamp with a J bolt 6 passing through hole 5 for
suspension of
(for example) pipework.
The load bearing characteristics of the conventional clamp are largely
unsatisfactory.
For example, a utility component suspended from the drop rod exerts a
significant
disruptive moment about the separate clamping region. Moreover for use on
tapered
beams, it is imperative that the set screw bites into the tapered face of the
flange (rather
than the horizontal face) otherwise installation may fail.
WO-A-00/52343 (Tyco European Metal Framing Limited) discloses a rigid clamp
comprising two C-shaped plates whose respective ends are connected by a boss.
Each
boss defines a path for receiving a drop rod so that when the clamp is located
on the
beam, the drop rod is inserted into the lower boss and is secured to the
underside of the
beam. Thus the drop rod becomes a load bearing element acting directly at the
clamping
region.
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The present invention seeks to improve clamps by incorporating first and
second jaws
having opposing contact surfaces which are relatively substantially linearly
displaceable
causing them to close securely in a substantially parallel manner onto
structural
elements of varying thickness. More particularly, the present invention
relates to a
clamp incorporating first and second jaws having opposing contact surfaces
which are
relatively substantially linearly displaceable and which exhibits high load
bearing
capabilities.
Thus viewed from one aspect the present invention provides a clamp comprising:
a first jaw and a second jaw having opposing contact surfaces which are
relatively substantially linearly displaceable between a position of minimum
separation
and a position of maximum separation, wherein in use the opposing contact
surfaces
contact the lower surface and upper surface respectively of a structural
element,
wherein the first jaw incorporates a first aperture remote from the contact
surface and
adapted to receive a suspension element or fastener;
one or more means for guiding the first jaw and the second jaw during
relative substantially linear displacement such as to substantially prevent
relative
non-linear displacement of the opposing contact surfaces; and
means for delimiting the substantially linear displacement of the opposing
contact surfaces of the first jaw and second jaw to the position of maximum
separation.
The relative substantially linear displaceability of the first and second jaw
advantageously makes the clamp suitable for high load uses.
The structural element is typically a beam (or a flange thereof) for which the
clamp may
be able to withstand a load of 1000kg (or more).
Typically the suspension element is a drop rod but numerous other suspension
elements
(such as J-bolts, set screws, wire elements) may be used. From the suspension
element
may be suspended utility components such as fixing brackets, pipe supports,
fire
protection equipment, cable trays, cables, wires, electrical conduits, heating
equipment,
ventilating equipment or air conditioning equipment. Equally the clamp of the
invention
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may be furnished with one or more piercings, apertures, slots and tabs either
for
suspending directly any of the previous utility components or for suspending
indirectly
from conventional means any of the above-mentioned utility components (but
especially electrical cables, pipes and wires from cable/wire clamps, clips
and ties or
hoses from snapper hose clamps).
Preferably the first jaw comprises a first reentrant body and the second jaw
comprises a
second reentrant body. Typically the first reentrant body is nested at least
partially
within the second reentrant body.
Preferably the first reentrant body is symmetrically nested at least partially
within the
second reentrant body. For example, the first reentrant body has a smaller
overall
dimension than the second reentrant body to enable it to be symmetrically
nested at
least partially within the second reentrant body. Generally the depth of the
second
I S reentrant body determines the strength of this embodiment and it is
preferred that the
second reentrant body is deeper than the first reentrant body. It is also
advantageous for
the first reentrant body to be composed of a material which is sufficiently
springy for it
to be snugly symmetrically nested at least partially within the second
reentrant body.
Typically for this purpose, the first reentrant body is composed of a material
which is
thinner than the material of which the second reentrant body is composed.
Alternatively preferably the first reentrant body is asymmetrically nested at
least
partially within the second reentrant body. The asymmetrically nested
arrangement
permits the first and second jaw to be manufactured with a substantially
identical
profile with advantageous cost savings.
Typically each reentrant body has a base between substantially parallel
opposed side
walls (which may be the same or different), a leading edge (that of the first
and second
reentrant body together defining a mouth) and a trailing edge (that of the
first and
second reentrant body together defining an open rear end). Preferably the
contact
surface of the (cg the first) or each (ie the first and second) reentrant body
has an
extended inner edge which in use abuts a surface (eg the leading edge) of the
structural
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element. This advantageously assists installation of the clamp by permitting
the installer
to push the extended inner edge against the leading edge of the structural
element and
steady the clamp for securement. The extended inner edge may adopt any shape
but
generally speaking will adopt a shape to conform to the leading edge of the
beam. Since
in most situations, the leading edge of the beam will be non-curved (eg
square), the
extended inner edge will be substantially perpendicular to the contact surface
(and
preferably extend substantially parallel to the direction of linear
displacement).
Preferably the first jaw comprises a first substantially U- shaped channel
member and
the second jaw comprises a second substantially U-shaped channel member. The
leading edge of the second substantially U-shaped channel member may have a
cut-away nose portion in its upper part. The leading edge of the first
substantially
U-shaped channel member may be chamfered or rounded into a "chin" in its lower
part.
Preferably the outer edge of the contact surface of either or (preferably)
both of the first
and second jaw is tapered or radiussed. This advantageously provides a
caroming
surface (or caroming surfaces) to assist the installer to manually bring the
contact
surfaces into contact with the upper and lower surface of the structural
element (eg by
locating the clamp adjacent the leading edge of the structural element and
applying firm
pressure to assist a "snap fit" using one hand). Where the outer edge of the
contact
surface of both of the first and second jaw is tapered or radiussed, the clamp
of the
invention may be advantageously secured to tapered upper and lower surfaces of
the
structural element. Where appropriate one or more faces of the first and/or
second jaw
may be ribbed or otherwise provided with strengthening means.
The means for delimiting the substantially linear displacement of the opposing
contact
surfaces of the first jaw and second jaw to the position of maximum separation
is
generally located between the extended inner edge of the contact surface of
the first and
second j aw and the trailing edge of the first and second j aw. The means for
delimiting
the substantially linear displacement of the opposing contact surfaces of the
first jaw
and second jaw to the position of maximum separation and one of the means for
guiding the first jaw and the second jaw during relative substantially linear
displacement may be the same.
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The one or more means for guiding the first jaw and the second jaw during
relative
substantially linear displacement are generally located at or between the
extended inner
edge of the contact surface of the first and second jaw and the trailing edge
of the first
5 and second jaw. In this location, they serve to arrest rotational moments
(ie rocking)
created as a reaction to clamping forces as the clamp is tightened.
Preferably a first means for guiding the first jaw and the second jaw during
relative
substantially linear displacement is located at or near to the extended inner
edge of the
contact surface of the first and second jaw. Particularly preferably a second
means for
guiding the first jaw and the second jaw during relative substantially linear
displacement is located at or near to the trailing edge of the first and
second jaw. More
preferably a first means for guiding the first jaw and the second jaw during
relative
substantially linear displacement is located at or near to the extended inner
edge of the
contact surface of the first and second jaw, a second means for guiding the
first jaw and
the second jaw during relative substantially linear displacement is located at
or near to
the trailing edge of the first and second jaw and a third means for guiding
the first jaw
and the second jaw during relative substantially linear displacement is
located between
the first and second means for guiding the first jaw and the second jaw during
relative
substantially linear displacement. This embodiment is particularly effective
in
preventing relative non-linear displacement (eg rocking) of the first and
second jaw.
One or more of the means for guiding the first jaw and the second jaw during
relative
substantially linear displacement comprises:
male and female portions on the first jaw and second jaw slidably engageable
in a
direction parallel to the direction of linear displacement.
Preferably the male and female portions comprise:
either (1) at least a part of the trailing edge of the first reentrant body
folded over at
least a part of the trailing edge of the second reentrant body or (2) at least
a part of the
trailing edge of the second reentrant body folded over at least a part of the
trailing edge
of the first reentrant body. Particularly preferably at least a part of the
trailing edge of
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the second reentrant body is folded over at least a part of the trailing edge
of the first
reentrant body. More preferably twin parts of the trailing edge of the second
reentrant
body extending parallel to the direction of linear displacement are folded
over twin
parts of the trailing edge of the first reentrant body extending parallel to
the direction of
linear displacement.
The extent to which the twin parts of the trailing edge of the second
reentrant body fold
over twin parts of the trailing edge of the first reentrant body may vary the
performance
of the clamp. Generally it is preferred that the extent to which the twin
parts of the
trailing edge of the second reentrant body fold over the twin parts of the
trailing edge of
the first reentrant body is large (eg such that the twin parts of the trailing
edge of the
second reentrant body are (or are almost) touching). Preferably the extent to
which the
twin parts of the trailing edge of the second reentrant body fold over the
twin parts of
the trailing edge of the first reentrant body is such that the twin parts of
the trailing edge
of the second reentrant body are overbent (eg inwardly overbent) which
advantageously
gives a locking effect.
Preferably the male and female portions comprise:
one or more elongate discontinuities extending parallel to the direction of
linear
displacement in the side of the second jaw slidably engageable with one or
more
elongate discontinuities extending parallel to the direction of linear
displacement in the
side of the first jaw. Particularly preferably the male and female portions
comprise:
first and second elongate discontinuities extending parallel to the direction
of linear
displacement in the opposing sides of the second jaw slidably engageable with
first and
second elongate discontinuities extending parallel to the direction of linear
displacement in the opposing sides of the second jaw.
)Jach elongate discontinuity may be an elongate depression in the exterior
face of the
side of the jaw. Preferred is a substantially V-shaped elongate depression.
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The male and female portions may be one or more (preferably two) tabs slidably
engageable with one or more (preferably two) elongate surfaces, slots or
apertures
extending parallel to the direction of linear displacement.
In a first preferred embodiment, the tab is inwardly dependent from a side of
the second
jaw and is slidably engageable with an elongate aperture extending parallel to
the
direction of linear displacement in a side of the first jaw. Particularly
preferably first
and second tabs are inwardly dependent from opposing sides of the second jaw
and are
respectively slidably engageable with first and second elongate apertures
extending
parallel to the direction of linear displacement in opposing sides of the
first jaw. The
axis of the or each inwardly dependent tab is typically substantially parallel
to the
direction of linear displacement.
In the first preferred embodiment, the elongate aperture determines the extent
of
relative substantially linear displacement of contact surfaces of the first
and second jaw
(ie acts as the means for delimiting the substantially linear displacement of
the opposing
contact surfaces of the first jaw and second jaw to the position of maximum
separation).
Alternatively in a second preferred embodiment, the tab is inwardly dependent
from a
side of the second jaw and is slidably engageable with the extended inner edge
of the
contact surface of the first jaw extending parallel to the direction of linear
displacement.
Particularly preferably first and second tabs are inwardly dependent from
opposing
sides of the second jaw and are respectively slidably engageable with first
and second
portions of the extended inner edge of the contact surface of the first jaw
extending
parallel to the direction of linear displacement. The axis of the or each
inwardly
dependent tab is typically perpendicular to the direction of linear
displacement.
Alternatively in a third preferred embodiment the tab is inwardly dependent
from an
edge (eg the edge between the extended inner edge and the trailing edge) of
the second
jaw and is slidably engageable with an elongate slot extending parallel to the
direction
of linear displacement in a side of the first jaw. Particularly preferably a
first tab is
inwardly dependent from an edge (eg the edge between the extended inner edge
and the
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trailing edge) of the second jaw and is slidably engageable with a first
elongate slot
extending parallel to the direction of linear displacement in a side of the
first jaw and a
second tab is inwardly dependent from an edge (eg the edge between the
extended inner
edge and the trailing edge) of the first jaw and is slidably engageable with a
second
elongate slot extending parallel to the direction of linear displacement in a
side of the
second jaw. It is preferred for the first and second tab to adopt a T-shaped
profile so
that the arms of the T extend beyond the edges of the elongate slot to provide
a locking
effect. Moreover by judicious positioning of the first and second tabs along
the edges
(eg the edges between the extended inner edge and the trailing edge), it is
possible for
the tabs to engage the fastener or suspension element to withstand rocking.
In the third preferred embodiment, the elongate slot determines the extent of
relative
substantially linear displacement of contact surfaces of the first and second
jaw (ie acts
as the means for delimiting the substantially linear displacement of the
opposing
contact surfaces of the first jaw and second jaw to the position of maximum
separation).
An edge of the first and/or second jaw between the extended inner edge and the
trailing
edge (cg in any of the first, second or third preferred embodiments but
especially the
third embodiment) preferably extends inwardly into a flange. By its
positioning, the
flange is adapted to be clear of the fastener or suspension element in
effective use and
for this purpose may be radiussed. By its positioning, the flange serves to
engage the
fastener or suspension element to withstand rocking.
Although the use of tabs and apertures/surfaces is adequate for normal loads,
it is
preferred for very high loads that one or more of the means for guiding the
first jaw and
the second jaw during relative substantially linear displacement comprises:
a securing member, wherein either ( 1 ) said securing member is secured to the
first j aw
and is slidably engageable with first and second collinear elongate apertures
extending
parallel to the direction of linear displacement in opposing sides of the
second jaw or
(2) said securing member is secured to the second jaw and is slidably
engageable with
first and second collinear elongate apertures extending parallel to the
direction of linear
displacement in opposing sides of the first jaw.
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Particularly preferably the securing member is secured to the second jaw and
is slidably
engageable with first and second collinear elongate apertures extending
parallel to the
direction of linear displacement in opposing sides of the first jaw.
The securing member may (for example) be a rivet passing through the collinear
apertures and fixed in a conventional manner (eg passing through a hole in the
side of
the jaw and secured exteriorly).
In a preferred embodiment, the clamp further comprises:
biassing means for biassing the first jaw and second jaw towards the position
of
minimum separation. The advantage of the biassing means is that it permits the
clamp
to be mounted in a "snap fit" action using one hand where it will be held in
place until
the fastener is fastened to secure the clamp more permanently. .
The biassing means may be a resilient biassing means. For example, the
resilient
biassing means may be a spring such as a compression or tensile spring (eg a
coiled or
flat spring), an elastomer or damping device. One end of the resilient
biassing means
may be fastened to one (or a part of one) of the means for guiding the first
jaw and the
second jaw during relative substantially linear displacement.
Where the securing member is secured to the second jaw and is slidably
engageable
with first and second collinear elongate apertures extending parallel to the
direction of
linear displacement in opposing sides of the first jaw, it is preferred that
one end of the
resilient biassing means is fastened to the securing member and the other to
an interior
surface of the first jaw (eg the base).
The first jaw may incorporate a first aperture rearwardly or forwardly of the
contact
surface. Preferably the first jaw incorporates a first aperture rearwardly of
the contact
surface. In a preferred embodiment, the second jaw incorporates a second
aperture
substantially collinear with the first aperture, wherein the first and second
aperture are
adapted to receive the suspension element or fastener.
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In use, the clamp of the invention may be secured to the structural element by
passing
the suspension element or fastener through the first aperture (and optionally
the second
aperture). The first and second aperture may be tapped or non-tapped to
receive a
5 threaded or non-threaded suspension element or fastener as desired.
The (or each) nut may be a standard hexagonal nut. The (or each) nut may be a
pressed
steel nut (eg in the form of a u- shaped threaded clip which may be slid onto
the base of
the jaw over the aperture so as to position the thread either internally or
externally). The
10 (or each) nut may be a rivetted nut such as a RIVNUTTM (cg a nut with a
short tubular
collar which may be tightly crimped, deformed or rivetted to attach to the jaw
to form a
female thread or may be loosely crimped, deformed or rivetted to attach to the
jaw but
remain rotatable).
Where the aperture itself is threaded, the material at the aperture may be
deformed or
shaped (eg by punching) to form the threaded portion. However, the aperture
may be
flow drilled (ie drilled using a special drill bit which generates frictional
heat sufficient
to render plastic the steel around the aperture so that it flows and deforms
into a thin
tube which may be tapped to form the threaded portion).
By way of example, the first aperture may be non-tapped and the suspension
element or
fastener may be fastened by a first hexagonal nut tightened against the
exterior surface
of the base of the first jaw and (optionally) a second hexagonal nut tightened
against the
interior surface of the base of the first jaw. Similarly, the second aperture
may be
non-tapped and the suspension element or fastener may be fastened by a first
hexagonal
nut tightened against the exterior surface of the base of the second jaw and
(optionally)
a second hexagonal nut tightened against the interior surface of the base of
the second
~ aw.
By way of a preferred example, the first aperture may be non- tapped and the
second
aperture may be punched or flow drilled to form the threaded portion or be
provided
with a nut (eg a pressed steel nut or rivetted nut). The fastener or
suspension element
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passes through the first aperture and engages the second aperture so that
subsequent
rotation draws together the first and second jaws advantageously without the
need for
actuating tools such as spanners.
By way of a preferred example, the first aperture may be flow drilled to form
the
threaded portion or be provided with a tightly crimped rivetted nut and the
second
aperture may be provided with a loosely crimped, rotatable rivetted nut. The
fastener or
suspension element rotates through the first aperture and second aperture to
the desired
height from where the rotatable, rivetted nut may be rotated to draw together
the first
and second jaw.
The contact surface of the first and second jaw will depend on the utility of
the clamp.
Where the structural element is a beam, the contact surface of the first jaw
and second
jaw is generally the surface of its edges (the "gums"). The edges may be
rolled or
folded to provide an enlarged contact surface in which there is advantageously
reduced
levels of localised stress.
The whole or a portion of the contact surface of either or both of the first
and second
jaw may be toothed. For example, the whole or a portion of the contact surface
of either
or both of the first and second jaw may be provided with a plurality of teeth
(eg
substantially V-shaped teeth (which may be angled or flattened) or
substantially
n-shaped teeth). Alternatively the whole of the contact surface of either or
both of the
first and second jaw may be smooth so as to provide an uninterrupted contact
which
avoids unsightly indentations on the surface of the structural element. In the
embodiment where the first and second jaw are asymmetrically nested, the
contact
surfaces of the first and second jaw are offset and the clamping effect may be
improved
by angling or stepping one or more of the teeth to accommodate the offset.
Suitable elongate fasteners are generally threaded fasteners (eg bolts) which
are
fastened with one or more (eg two) nuts.
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The first and second apertures may be any suitable shape such as round,
square,
pyramidal, ellipsoidal, rectangular and may be slotted. In the embodiment
where the
first and second jaw are asymmetrically nested, the first and second apertures
are
ellipsoidal to accommodate the asymmetry.
Typically, the clamp of the invention will be made from mild steel which is
optionally
clectro-zinc plated. More generally, the choice of material and dimensions
appropriate
for the purpose will be readily apparent to the skilled man.
In use, the first and second jaws of the clamp of the invention may be opened
manually
to an extent sufficient to capture between the opposing contact surfaces the
lower and
upper surfaces of a structural element (eg a beam). Where the leading edges of
the
contact surfaces is radiussed, they may be used as a caroming surface to force
open the
first and second jaws by pressing the mouth of the clamp against the leading
edge of the
structural element. The clamp may be steadied by bringing the leading edge of
the
structural element into contact with the extended inner edges of the first and
second
jaw. From this position, the first and second jaws are closed so that the
opposing
contact surfaces contact the lower surface and upper surfaces of the
structural element.
The clamp may be secured using the fastener passing through the aperture(s).
The invention will now be described in a non-limitative sense with reference
to
accompanying Figures 2 to 5 in which:
Figures 2a-c illustrates a first embodiment of the clamp of the invention at
positions of (a) minimum separation of the jaws (side and end views) and (b)
maximum
separation of the jaws (side and end views) and in (c) top view and Figure 2d
illustrates
an end view of the second jaw in isolation along section AA;
Figures 3a-c illustrates a second embodiment of the clamp of the invention
at positions of (a) minimum separation of the jaws (side and end views) and
(b)
maximum separation of the jaws (side and end views) and in (c) top view and
Figure 3d
illustrates an end view of the second jaw in isolation along section AA;
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Figures 4a and 4b illustrate a third embodiment of the clamp of the
invention at positions of minimum separation of the jaws (side and end views)
and
maximum separation of the jaws (side view); and
Figure Sa illustrates one of the two identical jaws of a fourth embodiment of
the clamp
of the invention illustrated in Figure Sb at a position of minimum separation
of the jaws
(side view).
A first embodiment of the clamp of the invention is illustrated in Figures 2a
(closed -
end and side view), 2b (open - end and side view) and 2c (top view) and is
designated
generally by reference numeral 1. The clamp 1 comprises a first jaw 2 in the
form of a
U-shaped body symmetrically nested partially within a second jaw 3 in the form
of a
U-shaped body. The U-shaped body of the first jaw 2 has a base 4 between
opposed
side walls Sa and Sb. The U- shaped body of the second jaw'3 has a base 7
between
opposed side walls 6a and 6b and is generally of a larger overall dimension
than the
first jaw 2. The trailing edge 10 of the second jaw 3 and the trailing edge of
the first jaw
2 bound an open rear end 30. The leading edge 11, 12 of the first and second
jaw 2,3
respectively together define a mouth 13. The upper part of the leading edge 12
of the
second jaw 3 is cut away into a nose portion. The lower part of the leading
edge of the
first jaw 2 is chamfered into a chin 17.
The first and second jaws 2,3 have opposing contact surfaces 8 and 9
respectively
which in use contact lower and upper surfaces of a structural element such as
a beam.
The opposing contact surfaces 8 and 9 are relatively substantially linearly
displaceable
(ie in direction X) between a position of minimum separation (see Figure 2a)
and a
position of maximum separation (see Figure 2b).
The opposing contact surfaces 8 and 9 are provided with a plurality of n-
shaped teeth
which serve to grip the lower and upper surface of the structural element. An
extended
inner edge 14 and 15 of each of the opposing contact surfaces 8 and 9
respectively
extend substantially parallel to the direction of linear displacement (X). An
outer edge
18 and 19 of each of the opposing contact surfaces 8 and 9 respectively are
radiussed.
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In order to guide the opposing contact surfaces 8 and 9 during relative
substantially
linear displacement (and to prevent rocking), there are provided three guiding
means:
(1) Tabs 20 and 21 inwardly dependent from the sides 6a and.6b of the second
jaw 3
(seen most clearly in the isolated view of the second jaw 3 in Figure 2d)
slidably engage
elongate apertures (only one of which is shown 22) in the first jaw 2
extending parallel
to the direction of linear displacement X. The length 1 of the elongate
aperture 22
delimits the linear displacement to the maximum separation illustrated in
Figure 2b;
(2) Elongate V-shaped depressions 23 and 24 in the second jaw 3 slidably
engage
corresponding elongate V-shaped depressions 25 and 26 in the first jaw 2; and
(3) Crescent shaped tabs (one of which only is shown as 200) inwardly
dependent from
the sides 6a and 6b of the second jaw 3 slidably engage extended inner edges
14 in the
first jaw 2.
In use, the first and second jaws 2,3 may be opened manually to an extent
sufficient to
capture between the opposing contact surfaces the lower and upper surfaces of
a
structural element (eg to the position shown in Figure 2a). Alternatively the
radiussed
outer edges 18 and 19 may be used as a camming surface to force open the first
and
second jaws 2, 3 by pressing the mouth 13 against the leading edge of the
structural
element. The clamp 1 may be steadied by bringing the leading edge of the
structural
element into contact with the extended inner edges 14, 15 of the first jaw 2
and second
jaw 3. From this position, the first and second jaws 2,3 are closed so that
the opposing
contact surfaces contact the lower surface and upper surfaces of the
structural element.
During the opening and closing steps, the relative linear movement of the
first and
second jaws 2,3 is guided by the guiding means described above which also
serve to
resist relative non-linear displacement (eg rocking).
The second jaw 3 is provided with an aperture 27 collinear with an aperture in
the first
jaw 2 (not shown). Each aperture is capable of receiving a suspension element
(not
shown) such as a drop rod which may be fastened to the first jaw 2 using a nut
28 and
to the second jaw 3 using a nut 29 in order to secure the clamp 1 to the
structural
element.
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1$
A second embodiment of the clamp of the invention is illustrated in Figures 3a
(closed -
end and side view), 3b (open - end and side view) and 3c (top view) and is
designated
generally by reference numeral 31. The clamp 31 comprises a first jaw 32 in
the form of
a U-shaped body symmetrically nested partially within a second jaw 33 in the
form of a
U-shaped body. The U-shaped body of the first jaw 32 has a base 34 between
opposed
side walls 35a and 35b. The U-shaped body of the second jaw 33 has a base 37
between
opposed side walls 36a and 36b and is generally of a larger overall dimension
than the
first jaw 32. The trailing edge 310 of the second jaw 33 and the trailing edge
of the first
jaw 32 bound an open rear end 330. The leading edge 31 l, 312 of the first and
second
jaw 32,33 respectively together define a mouth 313. The upper part of the
leading edge
312 of the second jaw 33 is cut away into a nose portion. The lower part of
the leading
edge of the first jaw 32 is chamfered into a chin 317.
The first and second jaws 32,33 have opposing contact surfaces 38 and 39
respectively
which in use contact lower and upper surfaces of a structural element such as
a beam.
The opposing contact surfaces 38 and 39 are relatively substantially linearly
displaceable (ie in direction X) between a position of minimum separation (see
Figure
3a) and a position of maximum separation (see Figure 3b).
The opposing contact surfaces 38 and 39 are provided with a plurality of n-
shaped teeth
which serve to grip the lower and upper surface of the structural element. An
extended
inner edge 314 and 315 of each of the opposing contact surfaces 38 and 39
respectively
extend substantially parallel to the direction of linear displacement (X). An
outer edge
318 and 319 of each of the opposing contact surfaces 38 and 39 respectively
are
radiussed.
In order to guide the opposing contact surfaces 38 and 39 during relative
substantially
linear displacement (and to prevent rocking), there are provided three guiding
means:
(1) Tabs 320 and 321 inwardly dependent from the sides 36a and 36b of the
second jaw
33 (seen most clearly in the isolated view of the second jaw 33 in Figure 3d)
slidably
engage elongate apertures (only one of which is shown 322) in the first jaw 32
extending parallel to the direction of linear displacement X. The length 1 of
the elongate
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16
aperture 322 delimits the linear displacement to the maximum separation
illustrated in
Figure 3b;
(2) Twin parts 340, 341 of the trailing edge 310 of the second jaw 33 which
fold over
the trailing edge of the first jaw 32; and
(3) Crescent shaped tabs (one of which only is shown as 300) inwardly
dependent from
the sides 36a and 36b of the second jaw 33 slidably engage extended inner
edges 314 in
the first jaw 32.
In use, the first and second jaws 32,33 may be opened manually to an extent
sufficient
to capture between the opposing contact surfaces the lower and upper surfaces
of a
structural element (eg to the position shown in Figure 3a). Alternatively the
radiussed
outer edges 318 and 319 may be used as a camming surface to force open the
first and
second jaws 32, 33 by pressing the mouth 313 against the leading edge of the
structural
element. The clamp 31 may be steadied by bringing the leading edge of the
structural
element into contact with the extended inner edges 314, 315 of the first jaw
32 and
second jaw 33. From this position, the first and second jaws 32,33 are closed
so that the
opposing contact surfaces contact the lower surface and upper surfaces of the
structural
element. During the opening and closing steps, the relative linear movement of
the first
and second jaws 32,33 is guided by the guiding means described above which
also
serve to resist relative non-linear displacement (eg rocking).
The second jaw 33 is provided with an aperture 327 collinear with an aperture
in the
first jaw 32 (not shown). Each aperture is capable of receiving a suspension
element
(not shown) such as a drop rod which may be fastened to the first jaw 32 using
a nut
328 and to the second jaw 33 using a nut 329 in order to secure the clamp 31
to the
structural element.
A third embodiment of the clamp of the invention is illustrated in Figures 4a
(closed -
end and side view) and 4b (open - side view) and is designated generally by
reference
numeral 41. The clamp 41 comprises a first jaw 42 in the form of a U-shaped
body
symmetrically nested partially within a second jaw 43 in the form of a U-
shaped body.
The U-shaped body of the first jaw 42 has a base 44 between opposed side walls
45a
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17
and 45b. The U-shaped body of the second jaw 43 has a base 47 between opposed
side
walls 46a and 46b and is generally of a larger overall dimension than the
first jaw 42.
The trailing edge 410 of the second jaw 43 and the trailing edge of the first
jaw 42
bound an open rear end 430. The leading edge 411, 412 of the first and second
jaw
42,43 respectively together define a mouth 413. The upper part of the leading
edge 412
of the second jaw 43 is cut away into a nose portion. The lower part of the
leading edge
411 of the first jaw 42 is chamfered into a chin 417.
The first and second jaws 42,43 have opposing contact surfaces 48 and 49
respectively
which in use contact lower and upper surfaces of a structural element such as
a beam.
The opposing contact surfaces 48 and 49 are relatively substantially linearly
displaceable (ie in direction X) between a position of minimum separation (see
Figure
4a) and a position of maximum separation (see Figure 4b).
The opposing contact surfaces 48 and 49 are provided with a plurality of n-
shaped teeth
which serve to grip the lower and upper surface of the structural element. An
extended
inner edge 414 and 415 of each of the opposing contact surfaces 48 and 49
respectively
extend substantially parallel to the direction of linear displacement (X). An
outer edge
418 and 419 of each of the opposing contact surfaces 48 and 49 respectively
are
radiussed.
In order to guide the opposing contact surfaces 48 and 49 during relative
substantially
linear displacement (and to prevent rocking), there are provided four guiding
means:
(1) Tabs 420 and 421 inwardly dependent from the sides 46a and 46b of the
second jaw
43 slidably engage the extended inner edge 414 of the first jaw 42;
(2) A rivet 470 extends laterally between the sides 46a and 46b of the second
jaw 43
and is fixed exteriorly thereto. The rivet 470 passes through collinear
elongate apertures
(only one of which is shown as 471) in the sides 45a and 45b of the first jaw
42;
(3) Twin parts (one or which only is shown as 480) of the trailing edge 410 of
the
second jaw 43 which fold over the trailing edge of the first jaw 42; and
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(4) Crescent shaped tabs (one of which only is shown as 400) inwardly
dependent from
the sides 46a and 46b of the second jaw 43 slidably engage extended inner
edges 414 in
the first j aw 42.
In use, the first and second jaws 42,43 may be opened manually to an extent
sufficient
to capture between the opposing contact surfaces the lower and upper surfaces
of a
structural element (eg to the position shown in Figure 4a). Alternatively the
radiussed
outer edges 418 and 419 may be used as a camming surface to force open the
first and
second jaws 42, 43 by pressing the mouth 413 against the leading edge of the
structural
element. The clamp 41 may be steadied by bringing the leading edge of the
structural
element into contact with the extended inner edges 414, 415 of the first jaw
42 and
second jaw 43. From this position, the first and second jaws 42,43 are closed
so that the
opposing contact surfaces contact the lower surface and upper surfaces of the
structural
element. During the opening and closing steps, the relative linear movement of
the first
and second jaws 42,43 is guided by the guiding means described above which
also
serve to resist relative non-linear displacement (eg rocking) in a most
effective manner.
The clamp 41 is biassed towards the closed position (Figure 4a) by a spring
490
attached at one end to the rivet 470 and at the other to the base 44 of the
first jaw 42.
This assists snap fit assembly. The clamp 41 may be provided with apertures,
fasteners
and nuts as described previously.
A fourth embodiment of the clamp of the invention is illustrated in Figure Sb
(closed -
end view) and is designated generally by reference numeral 51. The clamp 51
comprises
a first jaw 52 illustrated in isolation in Figure Sa in the form of a U-shaped
body
asymmetrically nested partially within a second jaw 53 which is identical in
profile to
the first jaw 52. The U-shaped body of the first jaw 52 has a base 54 between
opposed
side walls SSa and SSb containing an ellipsoidal aperture (not shown but
collinear with
the ellipsoidal aperture in the second jaw 53). Each aperture is capable of
receiving a
suspension element (not shown) such as a drop rod which may be fastened to the
first
jaw 52 using a nut and to the second jaw 53 using a nut in order to secure the
clamp 1
to the structural element. The trailing edge 510 of the first jaw 52 and the
trailing edge
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of the second jaw 53 bound an open rear end 530. The leading edge 511 of the
first jaw
52 and of the second jaw 53 together define a mouth. The lower part of the
leading edge
511 of the first jaw 52 is chamfered into a chin 517.
The first and second jaws 52, 53 have opposing contact surfaces 58 which in
use
contact lower and upper surfaces of a structural element such as a beam. The
opposing
contact surfaces 58 are relatively substantially linearly displaceable (ie in
direction X)
between a position of minimum separation (see Figure 5b) and a position of
maximum
separation.
The opposing contact surfaces 58 are provided with a plurality of n-shaped
teeth which
serve to grip the lower and upper surface of the structural element. An
extended inner
edge 514 of each of the opposing contact surfaces 58 extends substantially
parallel to
the direction of linear displacement (X). The edge between the trailing edge
510 and the
extended inner edge 514 extends inwardly into a flange 540 which is radiussed
540a.
An outer edge 518 of each of the opposing contact surfaces 58 is radiussed.
In order to guide the opposing contact surfaces 58 during relative
substantially linear
displacement (and to prevent rocking), there is provided a guiding means:
(1) T-shaped tab 520 inwardly dependent from an edge 56a of the first jaw 52
between
the trailing edge 510 and the extended inner edge 514 slidably engages an
elongate slot
522 in the second jaw 53 extending parallel to the direction of linear
displacement X.
In use, the opposing T-shaped tabs 520 and elongate slots 522 of the first jaw
52 and
second jaw 53 respectively are hooked together and aligned to lock the T-
shaped tabs
520 within the elongate slots 522. The length of the elongate slot 522
delimits the linear
displacement to the maximum separation. The first and second jaws 52, 53 may
be
opened manually to an extent sufficient to capture between the opposing
contact
surfaces 58 the lower and upper surfaces of a structural element.
Alternatively the
radiussed outer edges 518 may be used as a caroming surface to force open the
first and
second jaws 52, 53 by pressing the mouth 513 against the leading edge of the
structural
element. The clamp 51 may be steadied by bringing the leading edge of the
structural
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element into contact with the extended inner edges 514 of the first jaw 52 and
second
jaw 53. From this position, the first and second jaws 52, 53 are closed so
that the
opposing contact surfaces 58 contact the lower surface and upper surfaces of
the
structural element. During the opening and closing steps, the relative linear
movement
5 of the first and second jaws 52, 53 is guided by the guiding means described
above
which also serve to resist relative non-linear displacement (eg rocking). This
effect is
enhanced by the fact that rocking causes the T-shaped tabs 520 and the flanges
540
(which are carefully positioned) to impinge on the suspension element or
fastener so as
to withstand the turning moment. The anti-rotation effect of the T-shaped tabs
520 and
10 the flanges 540 increases as the jaws 52, 53 move apart linearly.
